I have a 2011 road glide and just upgraded to 19" agitators and low profile tire for front and 18" 200 for rear. I also went with a racetech front end spring and emulators. I still have the factory rear air shocks at about 35#. When I go over 75mph the front end starts swerving and becomes very unstable. It gets worse when behind a car or horrible behind an 18 wheeler. Also when I hit a small bump in the road it seems to bottom out. My expectations were a smoother ride and much better handling capability. My bike rode so well stock and everything I have read would make this upgrade an improvement. I weigh about 220 and the bike was loaded (tourpack and saddle bags). Any idea where we went wrong?
I hope I have this is the correct area and thanks for any help.

Same here. I have a 07 with a 21 on front, stock 16 on rear. On my last road trip I was getting the wobble/mini tank slapper feel when coming up behind 18 wheelers at 70 plus mph.
I have the tru link stablizer on the bike. The bike has 50k miles. I have had this same set up on the bike for the last 2 years.
Just confused why it has started doing this now..
Any ideas.

Just a guess here ~ MY RG is the most stable bike ever at hwy speeds ~ I'm thinkin you two have front tire issues, either balance or just a bad one. I have a tank slapper at 35 -40 with no hands on the bars but this is a neck bearing adjustment my dealer will cover under warranty.

I have read, that if your rear is Heavy, and your shocks are running low, the front gets light. I read this on website about rear shocks, but I'll be danged if I can find it again. Maybe put 10 more lbs of air in your shocks, and see what happens. I would be interested to see how true this is. It makes some kind of sense, if you bring the rear up, it will move the center of gravity forward.

Try 45 to 50 psi in rear shock what tire did you install I just replaced my stock dunlop with a mich. commander 2 had 19000 on stock wore good but never handled good seem sealer on road, bike was unstable instant handling upgrade with the commander its a little wider and shorter then stock

You did a lot all at once so you you need to check a few things. First check your tire pressure and if you have a second air gauge use it to compare the two. You would be surprised at how inaccurate cheap tire pressure gauges are. Second, if your bags are full and your running a heavy load increase the pressure in the rear shocks to 40-50 psi. Lastly, check the fall away on for steering head bearings. It may have been at the limit of being too loose with the oem wheel and suspension and now with the weight difference of the new wheel its just enough to cause the wobbly feeling.

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2011 RGU with more money then sence in it.
Oh and its black because blacks faster.